Re: [PATCH RFC V10 16/18] kvm hypervisor : Simplify kvm_for_each_vcpuwith kvm_irq_delivery_to_apic

[Raghavendra K T]

On 07/14/2013 06:54 PM, Gleb Natapov wrote:
> On Mon, Jun 24, 2013 at 06:13:53PM +0530, Raghavendra K T wrote:
> > Simplify kvm_for_each_vcpu with kvm_irq_delivery_to_apic
> >
> > From: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>
> >
> > Note that we are using APIC_DM_REMRD which has reserved usage.
> > In future if APIC_DM_REMRD usage is standardized, then we should
> > find some other way or go back to old method.
> >
> > Suggested-by: Gleb Natapov <gleb@xxxxxxxxxx>
> > Signed-off-by: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>
> > ---
> >   arch/x86/kvm/lapic.c |    5 ++++-
> >   arch/x86/kvm/x86.c   |   25 ++++++-------------------
> >   2 files changed, 10 insertions(+), 20 deletions(-)
> >
> > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> > index e1adbb4..3f5f82e 100644
> > --- a/arch/x86/kvm/lapic.c
> > +++ b/arch/x86/kvm/lapic.c
> > @@ -706,7 +706,10 @@ out:
> >   		break;
> >
> >   	case APIC_DM_REMRD:
> > -		apic_debug("Ignoring delivery mode 3\n");
> > +		result = 1;
> > +		vcpu->arch.pv.pv_unhalted = 1;
> > +		kvm_make_request(KVM_REQ_EVENT, vcpu);
> > +		kvm_vcpu_kick(vcpu);
> >   		break;
> >
> >   	case APIC_DM_SMI:
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 92a9932..b963c86 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -5456,27 +5456,14 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
> >    */
> >   static void kvm_pv_kick_cpu_op(struct kvm *kvm, int apicid)
> >   {
> > -	struct kvm_vcpu *vcpu = NULL;
> > -	int i;
> > +	struct kvm_lapic_irq lapic_irq;
> >
> > -	kvm_for_each_vcpu(i, vcpu, kvm) {
> > -		if (!kvm_apic_present(vcpu))
> > -			continue;
> > +	lapic_irq.shorthand = 0;
> > +	lapic_irq.dest_mode = 0;
> > +	lapic_irq.dest_id = apicid;
> >
> > -		if (kvm_apic_match_dest(vcpu, 0, 0, apicid, 0))
> > -			break;
> > -	}
> > -	if (vcpu) {
> > -		/*
> > -		 * Setting unhalt flag here can result in spurious runnable
> > -		 * state when unhalt reset does not happen in vcpu_block.
> > -		 * But that is harmless since that should soon result in halt.
> > -		 */
> > -		vcpu->arch.pv.pv_unhalted = true;
> > -		/* We need everybody see unhalt before vcpu unblocks */
> > -		smp_wmb();
> > -		kvm_vcpu_kick(vcpu);
> > -	}
> > +	lapic_irq.delivery_mode = APIC_DM_REMRD;
> Need to make sure that delivery_mode cannot be set to APIC_DM_REMRD
> from MSI/IOAPIC/IPI path.

I Gleb,
I need your help here since I do not know much about apic.

so are you saying explicitly checking that, kvm_set_msi_irq, 
apic_send_ipi, native_setup_ioapic_entry, does not have APIC_DM_REMRD as 
delivery_mode set?



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